Can anyone help with this engine sound. I cant tell if its the fan shroud or if its in the engine its self. Runs great but when you shut it down it sounds like metal hitting. Ive checked and checked and cant put my finger on it. It didnt start making the sound untill yesterday. Ive checked the valves and there fine. Anyone think they know what this might be. Here the video link.

http://www.youtube.com/watch?v=fc0AntsYWYY